1. Field of the Invention
This invention relates to a continuous, chemical vapor deposition method for producing a coated glass article, particularly, coated heat reflective architectural glass, and to the coated article so produced. In a specific embodiment, the invention relates to such a method for producing a glass article coated with a layer of silicon formed by treatment with a non-oxidizing gas comprising mono-silane (SiH.sub.4), and in some instances a mixture of mono-silane and ethylene (C.sub.2 H.sub.4), a titanium nitride layer formed on the silicon layer by mixing a titanium tetrahalide, e.g., TiCl.sub.4, with a reducing gas like ammonia and then reacting the gases at or near the surface of the silicon, and, on the titanium nitride layer, a second layer of silicon formed by treatment with a non-oxidizing gas comprising mono-silane or mono-silane and ethylene. The invention optionally includes the step of forming a protective layer, e.g., an abrasion resistant layer, on the second layer of silicon, which protective layer may comprise tin oxide.
2. The Prior Art
The production of architectural glass coated with silicon formed by continuous chemical treatment with a nonoxidizing gas comprising mono-silane is disclosed in U.S. Pat. No. 4,019,887, "Kirkbride et al.". The method disclosed by Kirkbride et al. is suitable for carrying out certain steps of the method of the instant invention, namely, that of forming a layer of silicon coating on a glass surface and on a titanium nitride coating.
The addition of ethylene to the Kirkbride et al. nonoxidizing gas comprising mono-silane is disclosed in U.S. Pat. No. 4,188,444 "Landau", as is a benefit derived from such use of ethylene, namely that the silicon coating has significantly improved resistance to alkali.
The use of ammonia and TiCl.sub.4 mixtures to produce titanium nitride coatings on glass by chemical vapor deposition is disclosed in U.S. Pat. No. 4,535,000, "Gordon".
The production of a glass article having a surface coated with a layer of silicon produced by the method of Kirkbride et al. and additionally coated with a layer of a metal oxide, deposited on the silicon, is disclosed by U.S. Pat. No. 4,100,330 "Donley".
Most architectural glass is produced by the "Float Glass Process", a part of which is shown in the drawings of Kirkbride et al. This process involves casting glass onto a molten tin bath which is suitably enclosed, transferring the glass, after it cools sufficiently, to rolls that are aligned with the bath, and cooling the glass as it is advanced on the rolls, first through a lehr and, finally, while exposed to ambient conditions. A non-oxidizing atmosphere is maintained in the float portion of the process, in contact with the tin bath, to prevent oxidation, while an air atmosphere is maintained in the lehr.
It will be appreciated that it would be advantageous, when it is desired to coat glass with silicon and titanium nitride and subsequently with tin or another oxide, to do so in conjunction with the production thereof by the float glass process. The glass is at a suitable temperature, as is disclosed by Kirkbride et al. and Gordon, in the float portion of the process for treatment to apply a silicon coating and a titanium nitride coating. It is also at a suitable temperature in some parts of the lehr, which contains air, for treatment of a surface thereof with an oxidizing gas comprising tetramethyl tin to form a tin oxide coating.